The unseen invaders: Tracking phylogeographic dynamics and genetic diversity of cryptic Pomacea canaliculata and P. maculata (Golden apple snails) across Taiwan

Abstract The cryptic invasion of golden apple snails (Pomacea canaliculata and P. maculata) in Taiwan has caused significant ecological and economical damage over the last few decades, however, their management remains difficult due to inadequate taxonomic identification, complex phylogeny, and limited population genetic information. We aim to understand the current distribution, putative population of origin, genetic diversity, and potential path of cryptic invasion of Pomacea canaliculata and P. maculata across Taiwan to aid in improved mitigation approaches. The present investigation conducted a nationwide survey with 254 samples collected from 41 locations in 14 counties or cities across Taiwan. We identified P. canaliculata and P. maculata based on mitochondrial COI and compared their genetic diversity across Taiwan, as well as other introduced and native countries (based on publicly available COI data) to understand the possible paths of invasion to Taiwan. Based on mitochondrial COI barcoding, sympatric and heterogeneous distributions of invasive P. canaliculata and P. maculata were noted. Our haplotype analysis and mismatch distribution results suggested multiple introductions of P. canaliculata in Taiwan was likely originated directly from Argentina, whereas P. maculata was probably introduced from a single, or a few, introduction event(s) from Argentina and Brazil. Our population genetic data further demonstrated a higher haplotype and genetic diversity for P. canaliculata and P. maculata in Taiwan compared to other introduced regions. Based on our current understanding, the establishment of P. canaliculata and P. maculata is alarming and widespread beyond geopolitical borders, requiring a concerted and expedited national and international invasive species mitigation program.


| INTRODUC TI ON
Invasive alien species are major drivers of biodiversity loss and have massive impact on the economic status of invaded countries (Linders et al., 2019;McNeely, 2001), even considered the second most economically destructive event after natural hazards such as earthquakes or floods (Turbelin et al., 2023).Making matters worse, morphologically similar species may invade together, causing a masking effect on species distribution and establishment, further hindering effective management practices (Saltonstall, 2002).
Without in-depth knowledge about the origins and population genetics of invasive species, management of natural landscapes and aquascapes is rendered speculative (Sakai et al., 2001).
Pomacea canaliculata, native to South America, have been both intentionally and unintentionally introduced in several countries (Lowe et al., 2000;Zhao et al., 2022), recently becoming a serious threat to agricultural and economic development worldwide (e.g., Asia, Europe, Africa, North America, and the Pacific Islands) (Buddie et al., 2021;Hayes et al., 2008;Ranamukhaarachchi & Wickramasinghe, 2006).Several other species of Pomacea (e.g., P. maculata, P. diffusa, P. scalaris) have also been introduced across numerous countries, and among the introduced species of Pomacea, P. canaliculata and P. maculata are the most destructive and morphologically cryptic (Rama Rao et al., 2018) causing frequent misidentifications.This lead to false biodiversity information, potentially obstructing effective invasion management (Cowie et al., 2006).
Taiwan encompasses a high percentage of the world's biodiversity compared to its landmass and houses an extraordinary array of fauna that comprises evolutionary lineages from both Palearctic and Indomalaya biogeographic realms (He et al., 2018;Päckert et al., 2009).However, as an island, Taiwan is highly sensitive to invasive species (Lee et al., 2019).Indeed, several invasive alien species have been introduced to Taiwan which has negatively affected its local biodiversity.Specifically, the introduction and establishment of P. canaliculata in Taiwan has resulted in serious ecological and economical destruction.
Subsequently, Pomacea spp.were introduced into other Asian countries for economic trade (food and aquarium trades).Initially, in Taiwan, Pomacea spp.were considered a healthy diet alternative that contained high protein, minerals, and vitamins, thus motivating farmers in its cultivation and trade (Cheng & Kao, 2006;Hayes et al., 2008).However, the trade of Pomacea spp. was soon terminated because of the snail's poor texture and high production cost.
Exacerbating Pomacea spp.invasion, farmers were not content with the low market value and thereafter released many Pomacea spp.into the neighboring countryside (Cheng & Kao, 2006;Chiu et al., 2014).
Almost immediately after release, Pomacea spp.became a serious threat to the local agricultural system possibly as a result of its high reproduction rate, tolerance to various environmental stressors, and voracious appetite (Joshi & Sebastian, 2003).The problem with Pomacea was first recognized in 1982, raising national-level attention due to numerous damage to local agronomy; Pomacea spp.spread into various agricultural lands, as well as natural wetlands impacting cultivated plants such as rice seedlings, taro, and lotus, even destroying several cultivation fields (Cheng & Kao, 2006).Making matters worse, Pomacea spp.acts as a vector for various zoonotic diseases (e.g., Angiostrongylus cantonensis).Several cases of human eosinophilic meningitis have been reported in Taiwan through either direct (consumption of raw snail meat) or indirect (contaminated food) involvement of Pomacea spp.(Tsai et al., 2001).More specifically, enormous annual economic losses were reported due to these invasive gastropods (Globally: 3.94 billion USD; in Asia: 3.71 billion since 1961; (Jiang et al., 2022)), with Asian countries as a few, introduction event(s) from Argentina and Brazil.Our population genetic data further demonstrated a higher haplotype and genetic diversity for P. canaliculata and P. maculata in Taiwan compared to other introduced regions.Based on our current understanding, the establishment of P. canaliculata and P. maculata is alarming and widespread beyond geopolitical borders, requiring a concerted and expedited national and international invasive species mitigation program.

T A X O N O M Y C L A S S I F I C A T I O N
Biogeography the predominantly affected region (Jiang et al., 2022).Across all reported gastropods, Pomacea spp.(particularly P. canaliculata) were noted to be the major contributors.Despite this, little attention has thus far been paid to understanding the invasive biology and population genetics of P. canaliculata in Taiwan (Banerjee et al., 2022;Cheng & Kao, 2006), which restricted the understanding of their regional (Taiwan) and potentially global spread (Sakai et al., 2001).
Originally, two species of Pomacea, P. canaliculata and P. scalaris, were reported from Taiwan, where P. canaliculata was noted as a destructive, dominant species and distributed nationwide.Conversely, P. scalaris was reported to be less invasive and limited in distribution to a few locations in Southern Taiwan (Cheng & Kao, 2006;Wu et al., 2010;Yang et al., 2018).However, a more recent molecular study revealed the presence of another species, P. maculata, hiding with its cryptic relative P. canaliculata in Southern Taiwan (Banerjee et al., 2022).Misidentification is very common between P. canaliculata and P. maculata based on morphological observation alone (Banerjee et al., 2022), suggesting limited knowledge of the true distribution and invasion history of P. maculata.In fact, out of the three Pomacea species currently in Taiwan, P. scalaris is considered less destructive due to its smaller hatching size and inferior growth performance (Wu et al., 2010), and thus assumed geographically restricted mostly in the South of the country (Wu et al., 2011).On the contrary, P. canaliculata and P. maculata are highly invasive and eco-economically destructive in nature, yet their actual distribution remains unknown across Taiwan (Banerjee et al., 2022).
Here, our study aims to generate accurate identification of cryptic invasive P. canaliculata and P. maculata, including their nationwide distribution and genetic diversity to better aid in adaptive management strategies.By doing so, we aspire to elucidate their (i) possible origin, thereby minimizing ongoing propagation events, and (ii) proper distribution and putative invasion path within Taiwan to maximize future eradication measures.As subsequent introductions of P. canaliculata and P. maculata may occur from trades between Taiwan into other Asian countries (e.g., China, Japan, Thailand, Malaysia) (Joshi & Sebastian, 2003), the current lack of molecular data makes global invasive management efforts especially difficult.Here too, our study may expand knowledge of Pomacea distributions in Taiwan.To accomplish these aims, our survey conducted collections across 41 different sampling locations within 14 counties or cities across Taiwan to reveal the origin, distribution, and population genetic structure of P. canaliculata and P. maculata.We then compared the genetic diversity of P. canaliculata and P. maculata with other countries (invaded or native) to understand their possible paths of invasion.

| Snail sample collection and preservation
In Taiwan, Pomacea spp.were presumably introduced through human activities and later distributed nationwide.Since this distribution may be affected by agricultural lands or other (human-induced) distribution barriers (e.g., roads, mountains), sampling locations (populations) were in agricultural lands centered around or near cities to understand the current nationwide distribution.We then further subdivided Taiwan into different regional parts coordinates (e.g., Southern, Northern, Eastern, Western, and Middle) to more generally understand the current distribution of Pomacea for downstream management decisions.To accomplish this, the distribution of Pomacea spp.were surveyed across 41 locations from 14 counties or cities in Taiwan, including Hualien (HU) and Taitung (TT) from the East; Yunlin (YL), Changhua (CH), Taichung (TC), and Miaoli (MIO) from the Middle of the island; Hsinchu (HS), Taoyuan (TY), Taipei (TP), and Yilan (YI) from the North; and Pingtung (PT), Kaohsiung (KSH), Tainan (TN), and Chiayi (CY) from the South.This was achieved via manual hand-collection within crop fields and drainage ditches from April 2020 to January 2023.Sampling locations and the number of samples are shown in Figure 1 and Appendix A. Collected samples were transported directly to the laboratory as soon as possible (as per sampling protocols).In cases of remote sampling or locations away from the laboratory, specimens were heat-shocked using hot water (100°C) for 10-15 min, washed and subsequently kept in an ice box in separate sampling bags to avoid cross-contamination.Once in the laboratory, samples were washed thoroughly to remove soil and debris, and then if not previously applied, were heat-shocked using a microwave to remove inner tissue from shells.After removing the inner tissue from the shell, 20-50 mg of foot tissue was used to extract DNA to avoid parasite contamination, and the rest of the tissue was stored in 95% ethanol.
were amplified from 41 sampling locations in Taiwan.

| Mitochondrial COI
The identification of 254 Pomacea spp. was accomplished via sequence similarity based on the NCBI database (https:// blast.ncbi.nlm.nih.gov/ Blast.cgi) with the highest level of query cover and percentage identity.To clarify the origins of our Pomacea spp.

| DNA polymorphism and phylogeographic distribution
All sequences were aligned in Mega v11 (Tamura et al., 2021) using the MUSCLE algorithm (Edgar, 2004), and DnaSP v6.12.03 (Rozas et al., 2017) was used to calculate the number of haplotypes (H) and polymorphic sites (S) as well as haplotype diversity (Hd), nucleotide diversities (π) and average number of difference (K).Neutrality tests such as Tajima's D and Fu's Fs (Fu, 1997) were performed to understand signatures of population expansion using Arlequin v3.5.2.2 (Excoffier & Lischer, 2010).Furthermore, to understand the level of genetic difference between the populations, pairwise F st values were calculated using Arlequin v3.5.2.2 (Excoffier & Lischer, 2010), and the level of gene flow/effective migration rate was calculated using the following formula: (Hudson et al., 1992).The connections between haplotypes and their phylogeographic distribution were analyzed using the median-joining network implemented in PopArt v1.7 (Leigh & Bryant, 2015).Furthermore, the mismatch distribution analyses were performed in DnaSP v6.12.03 (Rozas et al., 2017) to understand the genetic variation for the population of P. canaliculata and P. maculata.The inter-and intra-specific genetic distance (p-distance) of P. canaliculata and P. maculata were calculated using Mega v11 (Tamura et al., 2021).

| Species distribution
We used a quick identification primer (PanCOI, PinsCOI, and HCO2198) and full former region (LCO1490 and HCO2198), and both identified Pomacea spp up to species level.Based on our collections across Taiwan, the distribution of P. canaliculata and P. maculata was observed to be sympatric and heterogeneous.P. canaliculata was distributed throughout Taiwan and represented the dominant species (≈97%), whereas P. maculata represented ≈3% of the total number of collected individuals (Figure 1; Map created using "ArcGIS v10.7 software; ESRI Inc., Redlands, CA, USA").The genetic distance (p-distance) within P. canaliculata and P. maculata were 0.02 and 0.01, respectively, and genetic distance (p-distance) between them was 0.0928 (Appendix D).

| Phylogenic analysis
Phylogenetic relationships were congruent among four independent analyses (both ML and BI) with P. canaliculata and P. maculata clustered into two clades separately (Figure 2).P. maculata grouped with Pomacea occulta and Pomacea lineata and formed a sister group of P. canaliculata.although this separation was not strongly supported by maximum-likelihood analysis (<80, Figure 2).Furthermore, there were three clades noted for P. canaliculata (Clades A, B, and C) and two clades for P. maculata (Clades D and E).

| Phylogeography of Pomacea canaliculata in Taiwan
A total number of 246 sequences of P. canaliculata from 14 different cities/counties revealed the presence of 18 haplotypes (Pc_Hap1-18) and three different networks (Network Tw-A-C) across Taiwan (Figure 3, Tables 1 and 2 Compared to other cities/counties Tainan, Chiayi, Yilan, and Hualien were reported to have a higher number of shared and unique haplotypes (Tables 1 and 2).
F I G U R E 2 Phylogenetic tree generated from 254 sequences mitochondrial COI sequence of Pomacea canaliculata and P. maculata collected from 41 different locations (14 counties/cities) in Taiwan.Node labels are maximum-likelihood/Bayesian posterior probabilities.The sequences of P. lineata, P. paludosa, P. diffusa, P. scalaris, Marisa cornuarietis, Asolene platae, Saulea vitrea were used as outgroups.

| Phylogeography of Pomacea canaliculata worldwide
The combined mitochondrial COI datasets of P. canaliculata with 948 sequences across Africa, Asia, North America, Oceania, and South America were compared to one another and revealed the presence of a total of 65 haplotypes (Wc_Hap1-65) and three distinct networks (Network Wc-A-C) (Figure 4, Appendix F).The Network Wc-A, representing 32 haplotypes, including the most widely shared dominant Wc_Hap 1, and 31 unique haplotypes from Argentina 10,11,12,15,17), Taiwan (Wc_Hap 24,26,30,31,34)  in Dataset 1 (619 bp), however in the global dataset (Dataset 3 = 569 bp; 16 haplotypes from Taiwan) a slight decrease in the number of haplotypes was noted (Appendix G).Across all countries with sequences, the total number of unique haplotypes were found to be the most prevalent in Argentina, Uruguay, Philippines, China, and Taiwan.

| Phylogeography of Pomacea maculata in Taiwan
In Taiwan, eight sequences of P. maculata represented four different haplotypes, where Pm_Hap 19 (62.50%) was the most common and the other three haplotypes (Pm_Hap 20-22) were represented by single sequences (Table 3; Appendix E).Haplotype network analysis of P. maculata showed the presence of a single network, where Pm_ Hap 1 was a few mutational steps away; however, Pm_Hap 20-22 were more closely related (Figure 3).

| Phylogeography of Pomacea maculata worldwide
A total of 226 sequences of worldwide P. maculata revealed 46 haplotypes and seven different networks (Network Wm-A-G).
Furthermore, P. canaliculata in Taiwan was noted to significantly differ among some provinces, where a higher F st value (F st > 0.2) resulted in less gene flow (Nm < 1) and vice versa (Table 4).However, the negative F st values likely indicate more variation within the focal populations than between populations.While P. maculata was found to be less dominant in distribution compared to P. canaliculata, polymorphism in populations were higher (Table 4).The genetic diversity of P. canaliculata and P. maculata was considerably higher in their native countries (Argentina, Brazil, and Uruguay) compared to the places in which they were introduced.As an invaded region Taiwan demonstrated a higher genetic diversity of P. canaliculata and P. maculata, constituting of 16 haplotypes for P. canaliculata, and 4 for P. maculata (Tables 5 and 6).

| Mismatch distribution
The mismatch distribution results of P. canaliculata in Taiwan showed two bimodal well-separated peaks with some small intermediate peaks (Figure 6a).However, in the case of P. maculata three distinct peaks were observed, including two major peaks and an intermediate peak (Figure 6b).The mismatch distribution of P. canaliculata and P. maculata from the world dataset showed multimodal distribution (Figure 6c,d).

| DISCUSS ION
Based on our mitochondrial COI barcoding data, we found a wide distribution of P. canaliculata across Taiwan, whereas P. maculata was less abundant and restricted few counties (Pingtung, Kaohsiung, Tainan, and Chiayi, Miaoli, and Yilan) (Figure 1).Moreover, the distribution of P. maculata and P. canaliculata were noted to be sympatric and heterogenous across the country (Figure 1 and Table 1), a similar distribution pattern was noted in our previous study in southern Taiwan (Banerjee et al., 2022).Our haplotype analysis further demonstrated the possible origin of P. maculata from Argentina, although P. maculata may have been introduced independently from Argentina and Brazil (Hayes et al., 2008;Yang et al., 2022) instead of being imported directly from Brazil as reported in cases of P. maculata populations in China (Yang et al., 2018).Thus, the results from Yang et al. (2018Yang et al. ( , 2022) ) and this present study showed that the origin of P. maculata may be different in mainland China and Hong Kong, versus Taiwan.
Interestingly, the invasion of P. canaliculata and P. maculata has also been noted to be sympatric and heterogenous in other nearby Asian countries, such as in mainland China (Yang et al., 2018), Hong Kong (Yang et al., 2022), Malaysia (Rama Rao et al., 2018), and Thailand (Dumidae et al., 2021), where P. canaliculata is also reported to be more widely distributed compared to P. maculata.This corroborates the dominant hypothesis of predominately P. canaliculata in Asian regions (Hayes et al., 2008).Interestingly, this distribution pattern is not reflected in their native ranges, where P. maculata is routinely found to be widely distributed throughout Brazil, Uruguay, and Argentina, whereas P. canaliculata remains restricted to North Argentina and South Uruguay (Glasheen et al., 2020;Hayes et al., 2008).The difference in the distribution in Asian regions may reflect different physiological tolerance or species-specific biology (Hayes et al., 2008;Matsukura et al., 2016).Alternatively, it can be posited that these phylogeographical patterns and unequal distribution may be due to complex introduction histories.Notably, current distribution data is based on mitochondrial DNA, and P. canaliculata and P. maculata are reported to hybridize both in their native and non-native ranges (Glasheen et al., 2020;Kannan et al., 2021;Yang et al., 2020).Thus, hybridization could also play an important role in their unequal phylogeographic distribution.Similar to P. maculata, another invasive species, P. scalaris, was previously reported to be restricted to the southern part of Taiwan (Wu et al., 2010), however, we recorded some individuals from the middle region of Taiwan during our collection, possibly suggesting slow expansion.
Although the origin of P. canaliculata and P. maculata in Asia has been widely studied by previous researchers from different countries (Dumidae et al., 2021;Hayes et al., 2008;Liu et al., 2019;Yang et al., 2022), additional data from Taiwan specifically (and for the first time) will contribute to our knowledge regarding the possible path of introduction and spread.Our haplotype analysis revealed the presence of all three independent networks of P. canaliculata across Taiwan, whereas only two networks of P. canaliculata were detected from other countries of Asia (Yang et al., 2018(Yang et al., , 2022)).The occurrence of three largely different networks across Taiwan suggests introduction may have occurred multiple times and possibly propagated from multiple locations (Figure 3).
The combined mitochondrial datasets of P. canaliculata with 948 global sequences (originating from Africa, Asia, North America, Oceania, and South America) exhibited three different networks, mirroring previous studies (Yang et al., 2018;Yang et al., 2022), with sequences from Taiwan represented across all networks (Figure 4).
The Wc_Hap 1, Wc_Hap 27, and Wc_Hap 9 represented the founder haplotypes of Network Wc-A, Network Wc-B, and Network Wc-C, respectively.The common sharing of founder haplotypes between Taiwan and Argentina reaffirms the historical assumption of the introduction of P. canaliculata from Argentina to Taiwan (Hayes et al., 2008;Joshi & Sebastian, 2003).However, the absence of a shared haplotype from Argentina was noted in the case of WC_Hap 27 in Network Wc-B, which may simply be due to a smaller number of represented sequences from Argentina in our global dataset.
Furthermore, Network Wc-A and Network Wc-B were widely distributed, however, the haplotypes from Network Wc-C were rare in all native and non-native countries.This also does not lend support for sequence sampling bias (i.e., more representative samples in Taiwan compared to other sampled countries), although we cannot preclude it as a possible contributing factor.
Interestingly, our haplotype analysis revealed the presence of a single Network for P. maculata across Taiwan, echoing patterns across other Asian countries (Yang et al., 2018;Yang et al., 2022).This is in contrast to P. canaliculata for which the haplotype distribution pattern suggests multiple introduction events (Figures 3   and 5).Corroborating this further and despite the complex net- Unsurprisingly, the populations of P. canaliculata and P. maculata in Taiwan showed lower haplotype diversity compared to their native population counterparts (e.g., Argentina and Brazil) which can be the result of founder effects.However, compared with other Asian countries, Taiwan showed similar (e.g., China) or higher (e.g., Malaysia, Thailand, and Philippines) genetic diversity for P. canaliculata and P. maculata (Tables 5 and 6).These observations insinuate that Taiwan may have faced multiple introductions during the past.
Furthermore, as per our mismatch distribution analysis, two distinct peaks with large pairwise differences created a well-separated bimodal mismatch graph for P. canaliculata (Figure 6a), however, mismatch distribution analysis produced an intermediate peak in between the bimodal graph for P. maculata (Figure 6b).Those patterns canaliculata in Changhua, Taipei, and Hsinchu suggests a scarcity of rare alleles, however, these results may equally be due to sampling error.Furthermore, the significant difference in F st value (F st > 0.2) and negative F st values (suggesting more variation within the populations than in between) in Table 4 could be result of multiple introductions, human transportation, and population mixing.
Although the mitochondrial DNA haplotyping data is useful to understand the genetic diversity, as P. canaliculata and P. maculata are reported to hybridize, implementing nuclear genomic data or whole genomic sequencing data across invaded and native countries will be more useful for understanding invasion dynamics.The current datasets were limited in number and range of collections across different countries or regions, which could be solved by adding more precisely identified sample sequences.

| CON CLUS IONS
Our data suggested the Argentinian origin of P. canaliculata in Taiwan, whereas P. maculata might have both Argentinian and Brazilian origin.Comparing their introduction histories, current distribution, and cryptic nature of P. canaliculata and P. maculata, we assume that P. maculata may have been introduced along with P. canaliculata (either intentionally or unintentionally) in Taiwan, however, P. canaliculata likely has several introduction histories than P. maculata.Furthermore, our sampling across Taiwan, also reported the presence of P. scalaris (non-target for this study) within the middle region of Taiwan, which possibly suggests the expansion of another invasive species.Thus, the establishment of Pomacea spp.across all of Taiwan is alarming, and our current data suggests the urgent need for a nationwide mitigation program and proper management policy.
For early detection and to prevent further introductions and spread of multiple Pomacea species, eDNA-based methods have been previously demonstrated to be useful (Banerjee et al., 2022).

AUTH O R CO
(i) the sequences generated from the present study (samples only from Taiwan) represented 611 bp for P. maculata and P. canaliculata as Dataset 1, and global sequences (Taiwan and other previously published sequences collected from NCBI and/or Hayes
Networks were unique to Brazil.Among the shared haplotypes in Network Wm-A, all other Asian-originated haplotypes created a star-like structure around Wm_Hap 6 and Wm_Hap 1 which suggests those two haplotypes may have been TA B L E 2 Haplotype distribution (Pc_Hap) of Pomacea canaliculata in 14 counties/cities across Taiwan.

F
Mitochondrial COI haplotypes (Wc_Hap) revealing frequency and relationship of Pomacea canaliculata from the global dataset (Haplotype distribution (Pm_ Hap) of Pomacea maculata in 14 counties/ cities across Taiwan.
work of unique haplotypes, Taiwan shares the founder haplotype with Argentina (Wm_Hap 1).Notably, our results demonstrated the presence of Brazilian haplotypes with only a few mutational steps away from the founder haplotype (Wm_Hap 1), suggesting the introduction of P. maculata possibly originated via Argentina and Brazil, rather than solely from Brazil (Figure5).Similar findings were also noted in Hong Kong, where results fromYang et al. (2022) demonstrated P. maculata was possibly introduced from Argentina and Brazil.The presence of only a single network of P. maculata may suggest less frequent introduction events in Taiwan.

F
Mismatch distribution analysis of Pomacea canaliculata from (a) Taiwan (Dataset 1) and (c) the global dataset (Dataset 3); and P. maculata (b) Taiwan (Dataset 1) and (d) the global dataset (Dataset 2).suggest two episodes of population expansion which may coincide with multiple introductions for P. canaliculata, and possibly a single or continuous source for P. maculata.Furthermore, the multimodal mismatch distribution of P. canaliculata and P. maculata for the global dataset (Datasets 2 and 3) indicated their complex population expansion dynamics, and possibly introduction history, around several countries (Figure6c,d).Their genetic diversity (value of Hd, π, and K) varied among the counties/cities of Taiwan which may be related to multiple sources of introductions at different times, across different land-use patterns (e.g., agriculture), and human transportation.Moreover, the dispersal ability of Pomacea spp. is observed to be low and thus the widespread distribution across Taiwan within such a short invasion period was probably facilitated predominantly by human transportation.The neutrality test, such as the value of Fu's Fs and Tajima's D (D < 0), was not observed as significant for the overall population P. canaliculata and P. maculata in Taiwan, however, the higher value of Fu's Fs and Tajima's D (D < 0) for the population of P. canaliculata in Taitung, Miaoli, Yunlin, Taoyuan, Yilan, Kaohsiung, and Pingtung did demonstrate a high number of rare alleles.On the contrary, the lower value of Fu's Fs and Tajima's D (D > 0) for the population of P.
Number of sequences; S, Number of segregating sites; π, Nucleotide diversity.a Countries represented with 1 sequence were not shown here.Data of 139 samples were added from Yang et al. (2022), as their sequence is not available publicly yet.Population genetic diversity of Pomacea maculata from the global mitochondrial COI dataset (Dataset 2). b